Drug-resistant microbes emerging among urban poor

NEW YORK, June 16 (Reuters) The rate of skin and soft tissue infections that were resistant to most antibiotics, acquired in Chicago communities, increased rapidly between 2000 and 2005, researchers report.

Specifically, these infections, called methicillin-resistant Staphylococcus aureus (MRSA), and as the name implies, did not respond to methicillin, which is normally active against a wide spectrum of bacteria. These difficult to treat infections are often acquired in the hospital, usually by individuals with a weaken immune system, such as patients with cancer or HIV infection or the elderly.

''Community-associated MRSA infections have emerged among patients without health care-associated risk factors,'' Dr Bala Hota, of Rush University Medical Center, and colleagues, write in the Archives of Internal Medicine. ''Understanding the epidemiology of community-acquired MRSA is critical for developing control measures.'' The researchers performed a surveillance study analyzing soft tissue, abscess fluid, joint fluid, and bone cultures for S aureus at Cook County Hospital, a 464-bed public hospital, and its more than 100 associated clinics. The team estimated rates of infection and risk factors for community-acquired MRSA. Surveillance was conducted from January 1, 2000, through August 31, 2005.

S aureus was found in 2,346 soft tissue, abscess fluid, joint fluid, or bone specimens from 6,894 patients without health care-associated risk factors. Of these infections, 971 met the criteria for community-acquired MRSA.

The rate of community-acquired MRSA skin and soft tissue infections increased from 24.0 cases per 100,000 people in 2000 to 164.2 cases per 100,000 in 2005. Risk factors for infection included incarceration, African-American race, and residence at a group of public housing complexes. Older age was also tied to a increased risk of infection.

MRSA has emerged ''in addition to, not in place of, methicillin-susceptible Staphylococcus aureus,'' Hota's team notes.

They point out that control measures should focus on ''core groups that have contributed disproportionately to risk,'' but added that community-acquired MRSA becomes entrenched as it spreads in communities.

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